Assessment of resistance to cereal cyst nematode, stripe rust and powdery mildew in the wheat-Thinopyrum intermedium derivatives and their chromosome composition

Wide hybridization between wheat and wild relatives such as Thinopyrum intermedium is important for broadening genetic diversity and improving disease resistance in wheat. We developed 30 wheat-Th. intermedium derivatives. Here, we report assessments of their resistance to different pathogens including cereal cyst nematode (CCN, Heterodera spp.), Puccinia striiformis causing stripe rust, and Blumeria graminis f. sp. tritici inciting powdery mildew. Under natural field infection, all the wheat-Th. intermedium lines were resistant to at least one of the pathogens, and four lines were resistant to multiple pathogens. Twenty-nine out of 30 tested lines exhibited resistance to H. avenae, a dominant CCN species in wheat fields. Twenty-four lines were resistant to H. filipjevi, an emerging threat to wheat production. Tests of phenotypic responses in the naturally infected field nurseries identified six stripe rust resistant lines and 13 powdery mildew resistant lines. Mitotic observation demonstrated that these newly developed wheat-Th. intermedium derivatives included not only octoploid but also chromosome addition, substitution, and translocation lines. Chromosome compositions of the four lines resistant to multiple pathogens were analyzed by genomic in situ hybridization and fluorescence in situ hybridization. The octoploid lines Zhong 10-68 and Zhong 10-117 carried both intact Th. intermedium chromosomes and translocated chromosomes. Line Zhong 10-149 had 42 wheat chromosomes and two wheat ditelosomes plus a pair of T3BS·J translocated chromosomes. Line Zhong 10-160 carried 41 wheat chromosomes plus one pair of the J genome chromosomes of Th. intermedium. The multiple disease resistant wheat-Th. intermedium derivatives, especially lines with chromosome counts close to common wheat, provide valuable materials for wheat resistance breeding programs.

Diversity of Mycobiota Associated with the Cereal Cyst Nematode Heterodera filipjevi Originating from Some Localities of the Pannonian Plain in Serbia

Cereals, particularly wheat, are staple food of the people from the Balkans, dating back to the Neolithic age. In Serbia, cereals are predominantly grown in its northern part between 44° and 45.5° N of the Pannonian Plain. One of the most economically important nematodes on wheat is the cereal cyst nematode, Heterodera filipjevi. Cysts of H. filipjevi survive in soil for years and shelter a large number of microorganisms. The aims of this study were to investigate the diversity of mycobiota associated with the cereal cyst nematode H. filipjevi, to infer phylogenetic relationships of the found mycobiota, and to explore the ecological connection between fungi and the field history, including the potential of fungi in bioremediation and the production of novel bioactive compounds. Cysts were isolated from soil samples with a Spears apparatus and collected on a 150-µm sieve. The cysts were placed on potato dextrose agar, and maintained for two weeks at 27°C. Following fungal isolation and colony growing, the fungal DNA was extracted, the ITS region was amplified, and PCR products were sequenced. The study showed that the isolated fungal species belong to diverse phyla, including Ascomycota, Basidiomycota, and Mucoromycota. Ascomycota is represented by the families Clavicipitaceae, Sarocladiaceae, Nectriaceae, and Phaeosphaeriaceae. Basidiomycota is represented by the families Cerrenaceae, Polyporaceae, Phanerochaetaceae, and Meruliaceae, and the order Cantharellales. The family Mortierellaceae represents Mucoromycota. The members of Ascomycota and Basidiomycota both depict the field history. Ascomycota indicate the fungal infection is of recent origin, while Basidiomycota point toward the preceding host plants, enabling the plant field colonization history to be traced chronologically.

Wheat root protection from cereal cyst nematode (Heterodera avenae) by fluopyram seed treatment

Cereal cyst nematode (Heterodera avenae), an important plant-parasitic nematode causing yield losses on wheat, has been found in many provinces in China. It is urgent to develop an effective method to protect wheat from H. avenae damage. With a novel mode of action, fluopyram has been registered for controlling root-knot nematodes on cucumber and tomato in China. However, the bioactivity of fluopyram against H. avenae and whether seed treatment is effective in controlling H. avenae on wheat remains unknown. In this study, a bioactivity assay revealed that fluopyram increased the mortality of H. avenae second stage juveniles (J2), with LC50 and LC90 values of 0.92 mg L-1 and 2.92 mg L-1, respectively. Hatching tests showed that H. avenae egg hatching percent decreased 35.2-69.2% with fluopyram at the rate of 1.6-6.4 mg L-1, and the egg hatching period was delayed by 3-9 days compared with the control. In pot and field trials, fluopyram seed treatment significantly reduced H. avenae population density and increased wheat yield by 3.0-13.7%. Therefore, fluopyram seed treatment is an effective approach for the management of H. avenae on wheat in China.

The need for integrated management of the cereal cyst nematodes, Heterodera spp. in Central Western Asia and North Africa.

This chapter focuses on the economic importance, distribution, biology and symptoms of the cereal cyst nematode (CCN), Heterodera spp., in addition to recommended integrated nematode management (INM) tools to control CCN in wheat in Central Western Asia and North Africa.